New problem with new converter

Have a 95 Alpenlite Riviera 29ft 5ver. I replaced the failing Magnetek model 940 power converter today with a new Powermax pm3-35. After installed it operated perfectly at 14.5v for about 20 mins. Then the lights dimmed, started flickering like a candle flame.

I checked the voltage at the converter outputs and read a quick fluctuation between 9.5 and 10.7 volts.

Not sure why its doing it, but when i disconnect the plug from the ac outlet, then reconnect it, it goes back up to 14.5 volts for about another 20 mins. Then back to flickering lights and unstable low voltage output.

I've shut it down, unhooked and reconnected the output connections as well as the ground. Same thing occurs, 14.5 volts for 20 min then back to low unstable voltage.

One thing i noticed was a fixed voltage adjustment. Im not sure what that does or if i should do it. Documentation says it comes in 3 stage charging initially, the talks about moving a switch to fixed voltage adjustment and a potentiometer to adjust the voltage.

So anyway, thats where im at now, any help helps.